1. Field of the Invention
The present invention relates to a galectin-glycosaminoglycan complex and a method for controlling galectin activity.
2. Brief Description of the Background Art
The following abbreviations are used in this specification.    Gal: Galactose residue:    GlcNAc: N-Acetylglucosamine residue    NeuAc: N-Acetylneuraminic acid residue    GalNAc: N-Acetylgalactosamine residue    GlcA Glucuronic acid residue    6S: Sulfate group retained at the C6 position    α2-3: α2-3 Glycosidic linkage    β1-4: β1-4 Glycosidic linkage    β1-3: β1-3 Glycosidic linkage
Galectin is a general name for an animal lectin family proposed in 1992 (Barondes, S. H. et al., Cell, 76, 597-598 (1994)). Galectin are required to have binding specificity for β-linked galactose residue (hereinafter sometimes referred to as “β-galactoside”) and to have an amino acid primary sequence which characterizes the galectin family. As mammalian galectins, it has been proposed to call them by adding numbers in order of discovery (in order of register to GenBank). In accordance with this system, galectins 1 to 15 (kinds) have so far been found in mammals, and it is considered that they have their physiological functions in the living bodies by binding to various galactose-containing carbohydrates. Respective kinds of galectin have slightly different binding (recognizing) specificities for various galactose-containing oligosaccharide chains.
A total of 12 kinds of human-derived galectin families have so far been identified (Douglas N. W. Cooper, Biochimica et Biophysica Acta, 1572, 209-231 (2002)). That is, they are galectin-1 to 4 (Gal-1 to 4), galectin-7 to 10 (Gal-7 to 10) and galectin-12 (Gal-12). The members constituting this family are further divided into 3 subtypes based on their structures (Hirabayashi, J. et al., Glycobiology, 3, 297-304 (1993)).
Each of galectin-1, -2, -7 and -10 has a single carbohydrate recognizing region (carbohydrate-recognition domain; CRD) consisting of approximately from 130 to 140 amino acid residues, and belongs to the prototype. Galectin-3 has an amino-terminal domain, a type which is different from the carboxy-terminal CRD, and is the only one chimeric type. Each of galectin-4, -8, -9 and -12 has two CRDs connected via a linker peptide and is classified into a tandem repeat type.
Each of the prototype and chimeric type galectins has one CRD, and galectin-1, -2 and -3, and probably galactin-7 and -10 too, among them form a dimmer/multimer (polymer) and have a multivalent binding function, so that it is considered that they have a function to crosslink a complex carbohydrate (glycoconjugate).
Glycosaminoglycan is the carbohydrate moiety of proteoglycan among representative glycoconjugates (glycoprotein, glycolipid and proteoglycan) which are present as an extracellular matrix component and the like in the living bodies (JP-A-4-80201, JP-A-4-80202, JP-A-9-30979, JP-A-5-236951). About 10 kinds such as hyaluronic acid, chondroitin sulfate, keratan sulfate and the like are known as the glycosaminoglycan, and they have a characteristic common structure, namely an alternate repeating structure of N-acetylhexosamine and uronic acid (or galactose).
Frontal affinity chromatography (hereinafter sometimes referred to as FAC) is known as a method which can determine affinity between a biomaterial such as an enzyme or lectin and a substrate analog or oligosaccharide chain with high sensitivity and high accuracy.
FAC is a technique of affinity chromatography using liquid chromatography. In the FAC, in general, a column to which a certain molecule was immobilized is prepared, and a molecule to be interacted therewith is labeled with a fluorescent material and flowed as the solvent. When the elution front end (front) observed by a fluorescence detector is delayed than the case of unbinding molecule, the intermolecular affinity is determined by using the fact that degree of the delay is proportional to the intermolecular affinity (Seikagaku, 76(3), 256-268 (2004)).
In JP-A-2004-215612 and JP-A-2003-189874, binding of galectin to carbohydrates which are found in the “glycoprotein” and “glycolipid” among glycoconjugates is analyzed by making use of the FAC techniques, by eluting fluorescence-labeled carbohydrates through a galectin-immobilized column.